Plasmagon is an algorithmic choral piece. It's entirely a capella and has an ambient, environmental mood. Plasmagon was performed by eight samplers, controlled by custom software. It would be practically impossible for humans to perform it, due to its dynamic and rhythmic complexity.
Plasmagon has three unusual qualities: it doesn't have edges, it modulates stealthily, and it times modulations by listening to itself. No edges means no sharp attacks or decays, i.e. all sounds fade in and out gradually, yielding continuous harmonic gradation instead of easily distinguishable chords. Stealth modulation means that the key only changes by one note at a time, and only when that note isn't in use by any of the voices. The listener is a type of sensory feedback that monitors the output and detects optimal conditions for a modulation.
Plasmagon is generated by a combination of rules and polymeter. The polymeter consists of loops of differing lengths shifting phase relative to one another. Plasmagon uses fractional polymeter, i.e. the loop lengths aren't integer multiples of a common meter as is usually the case. For this reason in particular Plasmagon's phase-space (the range of variations before repetition occurs) is very large.
Plasmagon was originally developed as a musical accompaniment for the author's geometric visualizer, Whorld (see whorld.org). In the original installation, the same polymeter loops that control the choral voices also control Whorld's parameters, resulting in true synesthesia, i.e. the viewer sees the music and/or hears the visuals.
The progression is a cycle of neighboring keys, as follows:
E major / A major / D major / E melodic minor E major / B major / F# major / F# melodic minor
Timing of the first cycle (approximate): 00:00 E 01:30 A 02:20 D 05:20 Emin 08:00 E 09:40 B 10:30 F# 12:40 F#min 14:40 E